Power units with full CO2 utilization

The forecasts for the development of renewable energy and conventional energy with fossil fuels have significant discrepancies in quantitative indicators, but agree on the need to reduce CO2 emissions. In this direction, a great number of developments are associated with hydrogen energy. Alternative proposals are cycles on methane-oxygen fuel with CO2 capture from the concentrated stream at the outlet of the condenser-separator: high-temperature gas-steam turbine unit of CJSC SPC «Turbocon», Allam, and JIHT RAS cycle. A 100 kW gas-steam turbine with an initial mixture temperature of up to 800° C has been developed and tested. To develop a method for calculating steam condensers from a mixture with CO2 (common to all three schemes), tests were carried out on a special stand; the heat transfer coefficient experimental data have been used to design a highly efficient steam condenser from a mixture with a converging flow path to maintain its high speed, a heat transfer coefficient of 2700 W/m2K was achieved. It is planned to create a prototype installation containing a steam boiler, a gas-steam turbine and a steam condenser with CO2 capture from the concentrated stream at the compressor outlet.

BOILER PLANTS AND THE ENVIRONMENT PROTECTION FROM INDUSTRY HARMFUL EFFECTS

At present, environmental problems have become aggravated. The production process has a negative impact on the natural environment. It accumulates these harmful secondary effects. The degree of their harmful effects is increasing rapidly. The natural environment, taking into account its self-healing, undergoes dangerous, irreversible changes in its state. Now it is possible to talk only about slowing down this process. The ability to slow down and then stop the increase in the harmful impact on the natural environment is the essence of the nature conservation activities of humanity. It is necessary to move from a strategy of using the natural environment to a strategy of parity interaction with it. The problem was discussed at the Kyoto and Paris conferences of global importance. Among the branches of production, the most dangerous for the natural environment is energy. Its harmful effect is complex. Defending against it is a complex environmental issue. The adopted energy saving program actively contributes to solving the problem of saving the natural environment from degradation and death. The most environmentally aggressive element of power plants is solid fuel boiler plants. Reducing the intensity of their impact is the main direction of activities to protect the natural environment. The most difficult technical object is considered the power unit of a large thermal power plant. The most difficult part is the boiler plant. The most difficult element is the steam boiler. The level of environmental friendliness of the boiler is highly dependent on the degree of its wear. The problem of updating the fleet of boilers is of current importance. The general line of improving the environmental friendliness of production should be considered an increase in the level of environmental friendliness of power plants, especially those using fossil fuels, and a decrease in their emissions of carbon dioxide and heat. It is necessary to improve boiler installations, to increase their efficiency level, and the quality of their management. It is important to ensure the modernization of worn-out boiler installations based on their complete or partial renewal. In the formation of the power engineering of the future, the socio-psychological position of humanity must be radically changed.

Maximum Allowable Pressure Calculation of Water Tube Boiler during Operation

In the steam boiler industrial sector, pressure and temperature of the water tube are the two main factors that affect the safety and efficiency of a steam boiler. Explosions may be occurring because of a sudden drop in pressure without a corresponding drop in temperature. Therefore, understanding the temperature distribution of the water tube boiler is essential to control the failure and explosion of the boiler. Once the temperature distribution is known than the limiting factors that affect the water tube life such as the maximum allowable pressure can be determined. ANSYS software will be used to determine the temperature distribution in the water tube of a utility boiler during operation at elevated inlet water and furnace temperature. The theory of axisymmetric has been utilized since the water- tube is cylindrical in shape. In axisymmetric theory, a three-dimensional cylindrical problem like a water tube can be reduced to two-dimensional by ignoring the circumferential Ө, while the r-axis and z-axis became x-axis and y-axis or Cartesian coordinate. Then two-dimensional rectangular elements meshing for the profile cross-section along the water tube in r and z axes were implemented in a computerized simulation using ANSYS 10 to find out the steady-state temperature distribution of the water tube.

Improving the management of fuel combustion in ship boilers

Annotation – The article discusses the issues of increasing the efficiency of the combustion of liquid fuel in the furnaces of ship steam boilers using the proposed neural network system for automatic correction of the excess air coefficient. It is indicated that modern systems for automatic flame detection have a number of disadvantages, in particular, low sensitivity to extraneous illumination, etc. hot air or flue gases on the walls of the boiler furnace. Such pulsations reduce the reliability of the combustion monitoring and control system. Therefore, the task of developing and introducing on ships new, economically inexpensive and effective methods of effective control and management of the fuel combustion process in ship boilers using modern means of intelligent control is urgent. On the basis of the experiments carried out on a Mitsubishi MV 50 marine steam boiler and the collected experimental data, the values for training the neural network system of the air flow correction process, taking into account the color of the burner flame and the color of the flue gases, were obtained. The use of a trained neural network in the control system, taking into account the fuzzy expert system for monitoring the color of the flame and smoke, makes it possible to achieve the best excess air ratio depending on the steam load of the SEP units. Simulation modeling of the proposed neural system was carried out in a specialized program Matlab (Neural Networks Toolbox). The simulation results showed that the use of a neural network control system for the combustion of liquid fuel, using the example of a marine boiler, allows maintaining a given thermal regime over the entire range of steam load of the power plant units, and also allows timely correction of the excess air ratio, i.e. avoid excessive consumption of fuel.

Energy and Environmental Assessment of Steam Management Optimization in an Ethylene Plant

Steam crackers (ethylene plants) belong to the most complex industrial plants and offer significant potential for energy-saving translated into the reduction of greenhouse gas emissions. Steam export to or import from adjacent units or complexes can boost the associated financial benefit, but its energy and environmental impact are questionable. A study was carried out on a medium-capacity ethylene plant using field data to: 1. Estimate the energy savings potential achievable by optimizing internal steam management and optimizing steam export/import; 2. Quantify the associated change in air pollutant emissions; 3. Analyze the impact of the increasing carbon price on the measures adopted. Internal steam management optimization yielded steam let-down rate minimization and resulted in a 5% (87 TJ/year) reduction in steam cracker’s steam boiler fuel consumption and the associated cut of CO2 emissions by almost 4900 t/year and that of NOx emissions by more than 5 t/year. Steam import to the ethylene plant from the refinery proved to be purely economic-driven, as it increased the net fuel consumption of the ethylene plant and the refinery complex by 12 TJ/year and resulted in an increase of net emissions of nearly all considered air pollutants (more than 7000 t/year of CO2, over 15 t/year of NOx, over 18 t/year of SOx) except for CO, where the net change was almost zero. The effect of external emissions change due to the associated backpressure electricity production surplus (over 11 GWh/year) was too low to compensate for this increase unless fossil fuel-based electricity production was considered. The increase of carbon price impact on the internal steam management optimization economics was favorable, while a switch to steam export from the ethylene plant, instead of steam import, might be feasible if the carbon price increased to over 100 €/tCO2.

Efficiency of Installation of an Additional Gas-Air Heat Exchanger When Operating a Steam Boiler on Gas and Liquid Fuel

The article presents the results of calculating the efficiency of reconstruction of the gas and air paths of a steam boiler when working on gas and liquid fuel due to the installation of additional gas-air heat exchangers. Due to the utilization of the thermal energy of the flue gases in the newly installed heat exchangers, the air is heated in front of the boiler air heaters and the fuel efficiency is increased by increasing the boiler efficiency. The increase in the efficiency of the "gross" boiler during the operation of the considered TGM-84 boiler on fuel oil with an average annual operating mode was 2.81 %. The flue gas temperature after the boiler air heaters was 178 °C, and the air temperature at the inlet to the air heaters was 99 °C at the average annual load of the boiler, which ensures an almost corrosion-free operation of the air heater packing. It is revealed that when the liquid fuel boilers, installation of new heat exchangers and their strapping on the side of the air and flue gas has a shorter payback period than the boiler gas fired. The simple payback period of the considered technical solution was 6,82 years when working on gas fuel and 1,35 years when working on liquid fuel.

Matrix method to solve inverse problem of heat transfer in heat exchangers with phase transition in heat carriers

The transition to environmentally friendly and resource-saving energy, efficient use of natural resources and energy performance are the key priorities of the state energy policy of the Russian Federation. Maximum use of heat combustion of fuel and simultaneously production of condensate water of the combustion products of natural gas is one of the directions of energy saving policy. Despite many scientific papers on the issues of utilization of flue gas heat, condensation heat exchangers are not used in most gas boiler houses, energy power providers and thermal power plants in this country. And there are several reasons to explain this fact due to the lack of universal methods to calculate and design condensation-type heat exchangers. Thus, the development of new methods to simulate multithreaded heat exchangers considering the phase transition in heat carriers is an urgent task of power engineering and industry sectors. Matrix models of heat transfer based on mass and energy balance equations are applied to solve the inverse problem of heat transfer in heat exchangers, considering the phase transition in heat carriers. A method to calculate and select the designs of multi-threaded heat exchangers, considering the phase transition in heat carriers, has been developed. The author suggests a numerical solution to choose the design of a contact economizer of a heat power plant steam boiler used for heat recovery of flue gases to illustrate the effectiveness of the proposed method. The proposed method to solve the inverse problem of heat transfer provides the possibility to identify simultaneously the most acceptable values of the parameters of heat carriers and design characteristics of heat exchangers for various purposes.